CT scans expose you to significantly more radiation than mammograms. While mammograms deliver a relatively low dose of radiation—roughly equivalent to a couple of months of natural background radiation or a short airplane flight—CT scans involve much higher doses because they produce detailed cross-sectional images of the body using multiple X-ray measurements.
To understand this difference, it helps to look at what each imaging test does and how it works. A mammogram is a specialized X-ray of the breast designed to detect early signs of breast cancer. Modern mammography uses very low doses of radiation to produce high-quality images. The amount of radiation from a single mammogram is quite small, generally comparable to the natural radiation you receive from the environment over a few months. This low dose is considered safe for routine screening, and the benefits of early cancer detection far outweigh the minimal radiation risk.
In contrast, a CT (computed tomography) scan is a more complex imaging technique that takes multiple X-ray images from different angles around the body and combines them to create detailed 3D pictures of internal organs, bones, and tissues. Because CT scans cover larger areas and require multiple X-ray exposures, the radiation dose is much higher than that of a mammogram. For example, a chest CT scan can expose a person to radiation equivalent to several years of natural background radiation, depending on the scan type and settings.
The difference in radiation dose between the two can be roughly summarized as follows:
– **Mammogram radiation dose:** About 0.4 millisieverts (mSv), roughly equal to two months of natural background radiation or a cross-country flight.
– **CT scan radiation dose:** Varies widely depending on the type of CT, but a typical chest CT can be around 7 mSv or more, which is roughly 15 to 20 times higher than a mammogram.
This means that a CT scan exposes you to substantially more radiation than a mammogram. However, the higher radiation dose from CT scans is justified by the detailed and comprehensive diagnostic information they provide, which is often critical for diagnosing complex conditions.
It’s also worth noting that advances in technology have helped reduce radiation doses for both mammograms and CT scans. For mammography, digital and 3D tomosynthesis techniques maintain low radiation doses while improving image quality and cancer detection rates. For CT scans, newer machines and protocols aim to minimize radiation exposure without compromising diagnostic accuracy.
Despite the higher radiation dose from CT scans, the risk of radiation-induced harm remains low for most patients because these scans are used judiciously and only when medically necessary. Mammograms, on the other hand, are recommended regularly for women in certain age groups because the benefits of early breast cancer detection outweigh the very small radiation risk.
In summary, mammograms expose you to much less radiation than CT scans. Mammography uses a low dose suitable for routine screening, while CT scans involve higher doses due to their detailed imaging capabilities. Both tests are valuable diagnostic tools, and their use is carefully balanced against the radiation risks to maximize patient safety and health outcomes.
